I know that heat does do a good job but I'm thinking that by not being careful (I can do a good job of not being careful) could accidently fry/burn the gelcoat.A little heat makes it scrape off easier. Scraping is easier on the wood if you are carefull. Sanding can wear down the wood too much.
Which is why I ask and no answer, why take it all off and apply a new coat? ChuckCetol can be re-applied over old Cetol with only a light scuffing... I might simply dull it with some bronze wool or some 320 paper and then go back over the old with new.